a) Field of the Invention
The present invention relates to an apparatus for sensing a state of a battery such as charge and/or discharge state of the battery such as a lithium ion secondary battery.
b) Description of the Related Art
It is well known that the battery in an excessive charge/discharge state of the battery, e.g., the lithium ion secondary battery causes a deterioration of the battery so that a battery performance cannot be secured.
In addition, it is necessary to secure an intercellular balance in a lithium ion battery. Hence, if a group of cells to form the battery is manufactured, a, so-called, cell controller to make states of the respective cells of the battery (charge and discharge states) equal to each other is required.
However, a conventional cell controller requires a wide installation area with a large circuitry even if circuit parts are installed on electrodes of cell after the cell is manufactured.
A complicated wiring is needed to connect each cell to the cell controller and each cell has a mutually different potential. Hence, its circuit complexity is increased. In addition, it is difficult to install the circuit on laminated electrodes of such a bipolar cell or so forth.
Furthermore, the conventional cell controller consumes relatively largely a current in a sensing operation of, for example, discharge quantity.
There is a great possibility of accelerating a discharge of the battery in the discharge state. In this case, it is presumed that a battery performance cannot sufficiently be secured.
It is, hence, an object of the present invention to provide an apparatus for sensing a state of a battery in which a voltage-responsive optical sensing device such as a light emitting device, luminescent semiconductor micro-crystals and/or liquid crystal device to sense an excessive charge/discharge state of the battery can integrally and simply be installed into an inside of the battery without unnecessary wiring and the performance of battery can sufficiently be secured with less consumption of current.
According to one aspect of the present invention, there is provided an apparatus for sensing a state of a battery, the apparatus comprising: a voltage-responsive optical sensing device having an optical characteristic that changes in response to a variation in a voltage across positive and negative electrodes of a cell constituting the battery; and a state sensing system that senses a change in the optical characteristic of the voltage-responsive optical sensing device to sense the state of the battery.
This summary of the invention does not necessarily describe all necessary features so that the invention may also be a sub-combination of these described features.